fix ABA race in cond vars, improve them overall

[musl] / src / thread / pthread_cond_signal.c

diff --git a/src/thread/pthread_cond_signal.c b/src/thread/pthread_cond_signal.c
index e8ed71c..b26b8ce 100644 (file)
--- a/src/thread/pthread_cond_signal.c
+++ b/src/thread/pthread_cond_signal.c
@@ -2,8 +2,7 @@
 
 int pthread_cond_signal(pthread_cond_t *c)
 {
-       int w = c->_c_waiters;
-       if (a_swap(&c->_c_block, 0) || w)
-               __wake(&c->_c_block, 1, 0);
+       a_store(&c->_c_block, 0);
+       if (c->_c_waiters) __wake(&c->_c_block, 1, 0);
        return 0;
 }